As a conventional scroll compressor, for example, Japanese Patent No. 3909415 (Patent Literature 1) is known. This Patent Literature 1 has a description “a structure has: a crankshaft coupling an orbiting scroll member to rotational driving means of a drive part; a main shaft support part to support a main shaft part of the crankshaft on the compression chamber side from the rotational driving means; a member for placement of the main shaft support part; and a seal material to separate space forming the back side of the orbiting scroll member, into central space at approximately discharge pressure and outer peripheral space at pressure lower than the pressure of the central space, by pressure. A revolving shaft support part engaged with an eccentric pin part of the crankshaft is provided in the orbiting scroll member. The eccentric pin part is engaged with the revolving shaft support part so as to form a part of the central space in a status where an end surface of the eccentric pin part is opposite to the back face of the orbiting scroll member. Oil supply means to supply lubricating oil to the central space is provided, and almost all the lubricating oil supplied to the central space is returned through the main shaft support part on the opposite side to the compression chamber to a closed vessel bottom. As the main shaft support part, a rolling bearing is used. Further, the outer diameter of the central space separated with the seal material is smaller than the outer diameter of the rolling bearing”.
The structure is made to optimize an orbiting scroll pressing force to a fixed scroll while improve bearing reliability, and reduce mechanical sliding loss at a mechanical sliding part between the orbiting scroll and the fixed scroll so as to improve energy efficiency. Further, the structure is made to suppress excessive pressing with the mechanical sliding part so as to improve reliability (see paragraphs 0011 and 0012 of Patent Literature 1).